Hirabara Formation

[ Top ] [ Japanese ]

Hirabara Formation Katayama, 1939

Coherent formation
Late Triassic, Carnian (Fossils)

Sedimentary facies: Marine
Sedimentary facies: Bay opening toward south - southeast
Lithofacies: Conglomerate, Sandstone, Mudstone
Lithofacies: Conglomerate includes sedimentary rocks only with limestone. Igneous rocks are not included.
Lithofacies (Minor): Coal

Thickness: ca. 200 - 1,000 m
Upper limit: Disconformity (Momonoki Formation)
Lower limit: Angular unconformity (Tsunemori Formation)

Mine Group (Omine, Yamaguchi pref.)
[ Upper ]
?--?--?--?--?-
Asou Formation
--------------
Momonoki Formation
~~~~~~~~~~~~~~
Hirabara Formation
~~~~~~~~~~~~~~
[ Lower ]

Mine Group (Asa, Yamaguchi pref.)
[ Upper ]
?--?--?--?--?-
Kamoshiro Formation
--------------
Yamanoi Formation
--------------
Nakatsuka Formation
--------------
Idekami Formation
--------------
Hiramatsu Formation
?--?--?--?--?-
[ Lower ]

------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown

Distribution: Mine city, Yamaguchi pref.
Fossils: Marine reptiles (Fang), Fishes, Ammonoids, Insects, Plants, Bivalves (Anadontophora, Minetrigonia, Halobia), Brachiopods (Rhynchonella, Sakawairhynchia)

Maeda and Oyama (2019) Jour. Geol. Soc. Japan, vol.125, no.8, pp.585-594 DOI